1. Technical Field
The present invention relates to data storage systems in general, and in particular, to a method for maintaining volume configuration data within data storage systems. Still more particularly, the present invention relates to a method for generating sparse logical volume mirrors within data storage systems.
2. Description of the Related Art
A logical volume is a software abstraction of the underlying storage devices. A logical volume is a self-contained unit of storage exposed by an operating system and is administered by a logical volume manager. As an abstract of the physical topology of a storage system, a logical volume may be a fraction of a physical disk, an entire physical disk or even multiple physical disks. The logical volume manager presents the logical volume as a contiguous address space regardless of composition of the underlying physical storage devices.
Volume mapping is the process of mapping the contiguous logical address space presented by the logical volume manager onto the usually non-contiguous address space of the underlying storage devices. Volume mappings can be implemented either in hardware or in software.
Volume mappings may be used to increase the fault tolerance, performance, or capacity characteristics of the underlying storage devices. For example, a technique for improving fault tolerance, known as mirroring, uses volume mapping. With mirroring, when data is written to a first disk, the data is also written to a second disk; thus, the second disk is a “mirror image” of the first disk. Should the first disk fail, the second disk is still available for use and has an exact copy of the information on the first disk.
The present disclosure provides an improved method for generating logical volume mirrors such that the process of replicating volume information can be facilitated.